A large explosion rocked an ExxonMobil oil refinery in Montana on Saturday night, sparking a massive blaze at the site, reports said.

The blast happened around 10 p.m. at the refinery in Lockwood, just outside of Billings, the Billings Gazette reported.

The explosion prompted a massive response from several agencies.

No injuries have been reported, according to Yellowstone County Sheriff Mike Linder. 

The cause of the blast is under investigation. 

The Billings Fire Department said it was responding to a “structure fire” at the industrial plant.

Witnesses reported hearing a loud boom and seeing smoke and flames rising from the refinery.

The Billings Police Department was evacuating the area and urging people to stay away, according to KURL.